CVE-2026-74902: Siyuan-Note Siyuan

High severity, CVSS 8.6. EPSS: 0.2% chance of exploitation in the next 30 days.

SiYuan before v3.7.4 contains a cross-site scripting vulnerability in the file upload validation flow that fails to escape filenames before inserting them into HTML via insertAdjacentHTML. Attackers can craft a malicious filename containing script payloads that execute with full OS command access when a user drags, drops, or pastes the file into the editor.

Affected products

• Siyuan-Note Siyuan: before 3.7.4 (fixed in 3.7.4)

Published 2026-08-18. Last modified 2026-10-08.